Many parents desire to feed their infants, or have their infants fed, with breast milk from the birth mother. Occasionally, a breast-milk provider is unavailable to provide direct breast-feeding to the infant, and must therefore use pre-pumped breast milk stored in a bottle to feed the infant. Though numerous types of breast pumps exist, the easier the pump is for the provider to operate, the more relaxed, and therefore productive, the mother can be. Additionally, the more the pumping action of the pump replicates or resembles the sucking rhythm of an infant, the more easily milk will flow into a collection container.
Automated breast pumps generally operate with an electric motor that operates a pump such as a diaphragm or piston. Most hand-held automated pumps include a valve that opens the suction area between the breast and the pump to the external atmosphere. A motor drives a pumping mechanism so that the pump constantly attempts to remove air from between the pump intake and the breast. To simulate the suckling of an infant, the valve is alternatively opened and closed during pump operation. When the valve is closed, a pressure drop is created between the pump intake and the breast, and thus suction from the pump to the breast through a tube or hose. When the valve is opened, the suction is released to allow the breast to recover prior to the following suction cycle. During the suction cycle, the breast milk is drawn from the breast and falls through a flapper valve and into a collection article, such as a bottle.
To simulate the sucking rhythm of an infant, the valve is cycled open and closed for periods of time, usually only a few seconds each, to alternatively provide suction and release suction to the breast. Opening the valve allows the suction to the breast to be eliminated, but it takes time for the outside air to bleed into the system to fill the void created by the suction of the pump. The amount of time required to equalize pressure between the breast and the pump and the external atmosphere may depend on a number of criteria, such as the length of the tubing, the power of the pump motor, as well as other factors.
Additionally, some of the breast milk may pass beyond the flapper valve and fill the tubing between the collection bottle and the pump. Opening the valve may assist in allowing this breast milk to enter the bottle, but the likelihood of the breast milk in the tubing between the collection bottle and the pump being directed into the bottle upon the opening of the valve, and the normalization of pressure may depend on the length of the tubing, the positioning of the valve, and numerous other factors.